Numerical Investagation of a Castle-like Contour Plasmonic Nanoantenna with Operating Wavelengths Ranging in Ultraviolet–Visible, Visible Light, and Infrared Light

We propose a new design of a plasmonic nanoantenna and numerically study its optical properties by means of the 3D finite element method. The nanoantenna is composed of two identical castle-like contour nanometal-filled dielectric media inside the hollows. We examine the influence of the contour thickness, gap width, and dielectric media filled inside the hollows on the antenna resonance conditions. Through these simulations, we show that it is possible to tune an antenna with a constant length over a broad spectral range (ranging in ultraviolet–visible, visible light, and infrared light).     

Functional Contribution of Ca2+ and Mg2+ to the Intermolecular Interaction of Visinin-like Proteins

The interaction of human visinin-like protein 1 (VILIP1) and visinin-like protein 3 (VILIP3) with divalent cations (Mg²⁺, Ca²⁺, Sr²⁺ and Ba²⁺) was explored using circular dichroism and fluorescence measurement. These results showed that the four cations each induced a different subtle change in the conformation of VILIPs. Moreover, VILIP1 and VILIP3 bound with Ca²⁺ or Mg²⁺ in a cooperative manner. Studies on the truncated mutants showed that the intact EF-3 and EF-4 were essential for the binding of VILIP1 with Ca²⁺ and Mg²⁺. Pull-down assay revealed that Ca²⁺ and Mg²⁺ enhanced the intermolecular interaction of VILIPs, and led to the formation of homo- and hetero-oligomer of VILIPs. Together with previous findings that Ca²⁺-dependent localization of VILIPs may be involved in the regulation of distinct cascades and deprivation of Ca²⁺-binding capacity of VILIPs did not completely eliminate their activity, it is likely to reflect that Mg²⁺-bound VILIPs may play a role in regulating the biological function of VILIPs in response to a concentration fluctuation of Ca²⁺ in cells.     

Recombinant dioscorins of the yam storage protein expressed in Escherichia coli exhibit antioxidant and immunomodulatory activities

Dioscorins, the major storage proteins in yam tubers, exhibit biochemical and immunomodulatroy activities. To investigate the potential application of dioscorins in biomedical research, we expressed the dioscorin genes Dj-dioA3 and Dp-dioA2 from Dioscorea japonica and Dioscorea pseudojaponica, respectively, in E. coli and routinely obtained approximately 15mg proteins per liter Escherichia coli culture (mg/L) to 30mg/L of rDj-dioscorinA3 and 4 to 8mg/L of rDp-dioscorinA2. Western blot analyses revealed that both recombinant dioscorins contained epitopes with similar antigenicities to those of the native dioscorins. Results from dithiothreitol (DTT) treatment followed by monobromobimane (mBBr) staining showed that both recombinant dioscorins, like the native dioscorins, contain an intramolecular disulfide bond between Cys(28) and Cys(187) residues. Circular dichroism spectroscopy findings indicated that the secondary structural contents of the recombinant dioscorins showed high similarity to those of their corresponding native dioscorins. Both recombinant dioscorins, like the native dioscorins, exhibited 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and Toll-like receptor 4 signaling activities, and stimulated the phagocytosis of E. coli by macrophage. Overall, our results indicated that substantial amounts of recombinant dioscorins can be purified easily from E. coli and that these recombinant dioscorins are appropriate for application in future investigations of the biomedical functions of dioscorins.     

Influencing effect of intra-granule mass transfer in expanded granular sludge-bed reactors treating an inhibitory substrate

Two expanded granular sludge-bed (EGSB) reactors (superficial velocity u s=6.0 and 9.0m/h) were used to treat an inhibitory substrate phenol. The granule diameter (dp) increased with increasing organic loading rate (OLR) and u(s). At the OLRs of 1.67-4.44 kg phenol/m3 d, the accumulation of volatile fatty acids (VFAs) was insignificant; whereas at the OLR of 5.11 kg phenol/m3 d, both the accumulation of VFAs and the washout of large hollow granules (average dp=2.90-3.12 mm) occurred. The comparative experimental and simulated results showed that the proposed kinetic model is suitable for design and predicting purposes. The calculation results of mass transfer parameters (Thiele modulus, Biot number, diffusion layer thickness, and overall effectiveness factor) and parametric sensitivity analysis results (half-saturation constant Ks and dp) showed that the intra-granule mass transfer would lead to a more influencing effect than the external mass transfer on the overall substrate removal rate in EGSB reactors.     

南方4种草本植物对铝胁迫生理响应的研究

 不同的植物对铝胁迫的生理响应不同, 因而对铝毒的耐性也不相同。设置5种铝浓度,进行砂培法处理,研究了4种我国南方红壤广泛分布的草本植物——牵牛(Pharbitis nil)、望江南(Cassia occidentlis)、光头稗(Echinochloa colonum)和合萌(Aeschynomene indica)的种子萌发、光合色素、脯氨酸含量、丙二醛(MDA)含量、可溶性糖(SS)含量、质膜透性(MP)、过氧化氢酶 (CAT) 活性以及过氧化物酶 (POD)活性的变化。结果表明铝对4种植物的生理特性都有明显的影响。4种植物的种子在10 000 mg·L－1 Al3+处理条件下都不能萌发。2 000 mg·L－1 Al3+处理都不利于4种植物的生长,与对照相比,2 000 mg·L－1 Al3+处理时4种草本植物叶绿素和叶绿素总含量显著降低(p<0.05);MDA含量和MP显著增加(p<0.05);脯氨酸含量极显著增加(p<0.01);POD和CAT活性极显著降低(p<0.01)。中低铝(80和400 mg·L－1)处理时,牵牛和合萌与对照相比,MP和MDA含量降低,POD和CAT活性升高;望江南的反应与牵牛和合萌的反应相反;光头稗在80 mg·L－1 Al3+处理时,与牵牛和合萌的变化一致,在400 mg·L－1 Al3+处理时,则相反。植物在中低铝处理条件下,通过维持较高的POD和CAT活性和脯氨酸、叶绿素含量,较低的MP和MDA含量来增加其对铝的耐性。     

ENU mutagenesis identifies mice with morbid obesity and severe hyperinsulinemia caused by a novel mutation in leptin

Background

Obesity is a multifactorial disease that arises from complex interactions between genetic predisposition and environmental factors. Leptin is central to the regulation of energy metabolism and control of body weight in mammals.

Methodology/Principal Findings

To better recapitulate the complexity of human obesity syndrome, we applied N-ethyl-N-nitrosourea (ENU) mutagenesis in combination with a set of metabolic assays in screening mice for obesity. Mapping revealed linkage to the chromosome 6 within a region containing mouse Leptin gene. Sequencing on the candidate genes identified a novel T-to-A mutation in the third exon of Leptin gene, which translates to a V145E amino acid exchange in the leptin propeptide. Homozygous Leptin^145E/145E mutant mice exhibited morbid obesity, accompanied by adipose hypertrophy, energy imbalance, and liver steatosis. This was further associated with severe insulin resistance, hyperinsulinemia, dyslipidemia, and hyperleptinemia, characteristics of human obesity syndrome. Hypothalamic leptin actions in inhibition of orexigenic peptides NPY and AgRP and induction of SOCS1 and SOCS3 were attenuated in Leptin^145E/145E mice. Administration of exogenous wild-type leptin attenuated hyperphagia and body weight increase in Leptin^145E/145E mice. However, mutant V145E leptin coimmunoprecipitated with leptin receptor, suggesting that the V145E mutation does not affect the binding of leptin to its receptor. Molecular modeling predicted that the mutated residue would form hydrogen bond with the adjacent residues, potentially affecting the structure and formation of an active complex with leptin receptor within that region.

Conclusions/Significance

Thus, our evolutionary, structural, and in vivo metabolic information suggests the residue 145 as of special function significance. The mouse model harboring leptin V145E mutation will provide new information on the current understanding of leptin biology and novel mouse model for the study of human obesity syndrome.     

Skin Commensal Staphylococci May Act as Reservoir for Fusidic Acid Resistance Genes

We analyzed the occurrence and mechanisms of fusidic acid resistance present in staphylococci isolated from 59 healthy volunteers. The fingers of the volunteers were screened for the presence of staphylococci, and the collected isolates were tested for resistance to fusidic acid. A total of 34 fusidic acid resistant staphylococcal strains (all were coagulase-negative) were isolated from 22 individuals (22/59, 37.3%). Examination of the resistance genes revealed that acquired fusB or fusC was present in Staphylococcus epidermidis, Staphylococcus capitis subsp. urealyticus, Staphylococcus hominis subsp. hominis, Staphylococcus warneri and Staphylococcus haemolyticus. Resistance islands (RIs) carrying fusB were found in S. epidermidis and S. capitis subsp. urealyticus, while staphylococcal chromosome cassette (SCC)-related structures harboring fusC were found in S. hominis subsp. hominis. Genotypic analysis of S. epidermidis and S. hominis subsp. hominis indicated that the fus elements were disseminated in diverse genetic strain backgrounds. The fusC elements in S. hominis subsp. hominis strains were highly homologous to SCCfusC in the epidemic sequence type (ST) 239/SCCmecIII methicillin-resistant S. aureus (MRSA) or the pseudo SCCmec in ST779 MRSA. The presence of acquired fusidic acid resistance genes and their genetic environment in commensal staphylococci suggested that the skin commensal staphylococci may act as reservoir for fusidic acid resistance genes.